1. Field of the Invention
The present invention relates to a new class of compounds of five membered heterocyclic ring compounds and to their use in treatment of diabetes and related illnesses. More particularly the invention relates to compounds of this series, methods for their preparation, pharmaceutical composition containing these compounds and their use in the treatment of complications of diabetes mellitus. The compounds of this series exhibit AGE breaking and inhibiting activity, which is essential for the treatment of diabetic and aging-related vascular and neurovascular complications including kidney disease, nerve damage, atherosclerosis, retinopathy, inflammatory disorders, immunological disorders, oxidative stress and dermatological & cosmetic indications.
The invention also extends to the method of reversing the discoloration of teeth resulting from nonenzymatic browning in the oral cavity by administration of an effective amount of these compounds to reverse preformed advanced glycosylation crosslinks.
These compounds, also exhibit free radical scavenging activity and hence are useful in the treatment of diseases caused by free radicals besides their cosmetic applications
The triple function of a free radical scavenger, AGE breaker and AGE inhibitor of these compounds can be effectively used in cosmetic compositions which are capable of arresting and reversing the process of skin aging resulting from an increased accumulation of advanced glycation end-products (AGEs) on the skin proteins and photo damage through free radical actions. The invention further relates to composition and method for scavenging free-radicals from the body cells.
2. Description of the Related Art
Maillard in 1912 found that reducing sugars, such as glucose and ribose react with proteins to form brown pigments. Further studies have shown that this is an irreversible non-enzymatic reaction, which occurs in several natural systems including stored foodstuff. Maillard reaction occurs in two stages, early and advanced. Initially, proteins react with glucose to form stable Amadori products, which subsequently cross-links to form advanced glycation end products (AGE). In most cases, the formation of AGE also accompanies browning of the proteins and increase in the fluorescence.
In diabetes, where blood glucose level is significantly higher than normal, the reaction of glucose with several proteins such as hemoglobin, lens crystallin and collagen, gives rise to the formation of AGE, which in turn, is responsible for the complications associated with diabetes, such as nephropathy, microangiopathy, endothelial dysfunction and other organ dysfunctions. In addition, the activity of several growth factors, such as basic fibroblast growth factor, is also impaired, AGE products, unlike normal proteins in tissue, have a slower rate of turnover and replenishment. It has been reported that AGE products may in fact elicit a complex immunological reaction involving RAGE (Receptor for Advanced Glycation End Products) receptors and activation of several incompletely defined immunological processes. It has been documented that diabetes with evidence of microangiopathy and macroangiopathy also show evidence of oxidative stress, the mechanism of which has not been elucidated.
In vitro AGE formation can be studied in the laboratory by incubating reducing sugars, such as ribose or glucose with bovine serum albumin. AGE formation can be detected by increase in the fluorescence or increased cross reactivity with anti-AGE antibodies. The increase in fluorescence seems to precede formation of AGE specific antigenic epitopes. This increase in fluorescence is used to monitor the increased AGE formation in vitro (Brownlee M et al, Science 1986; 232:1629–1632). In addition to the increase in the fluorescence, one of the most important features of in vitro AGE formation is the formation of antigenic epitopes that are specific to AGE and not to the native proteins. Therefore, it is possible to raise antibodies against advanced glycation end products of one protein and use them to detect AGE formation in other proteins. This has served as an important analytical tool in AGE research.
Due to the clinical significance of AGE formation, many approaches are being used to diagnose, prevent, or revert AGE formation in the body. The formation of AGE could be inhibited by reacting with an early glycosylation product that results from the original reaction between the target protein and glucose. The inhibition was believed to take place as the reaction between the inhibitor and the early glycosylation product appeared to interrupt the subsequent reaction of the glycosylated protein with additional protein material to form the cross linked late stage product. Compounds like aminoguanidine act to inhibit AGE formation by such mechanism.
The formation of AGE on long-lived proteins is also associated with cross-linking of these proteins. The AGE derived protein cross-links have been shown to be cleaved by compounds like N-phenacyl thiazolium bromide (PTB), which reacts with and cleaves covalent, AGE derived protein cross links (Vasan et al. Nature 1996; 382: 275–278 ; U.S. Pat. No. 5,853,703, Date of Patent: Dec. 29, 1998). The mechanism of reducing the AGE content in tissues is expected to take place relatively rapidly, in contrast to aminoguanidine, which acts slowly by its very nature of mechanism of action.
The compounds which are AGE breaker or AGE inhibitor are of prime importance in therapeutic applications as mentioned below:
AGE Breakers:
The compounds which can break the accumulated AGE can be used as a medicament in the treatment of diabetic complications and aging-related diseases caused by accumulation of AGE.
The compounds which can inhibit accumulation of AGE by breaking AGE, can be used as a medicament for arresting the aggravation of diseases such as diabetes and aging related complications caused by accumulation of AGE.
AGE Inhibitors:
The compounds which can inhibit accumulation of AGE by inhibiting formation of AGE, can be used in a medicament for the diseases such as diabetes and aging related complications caused by accumulation of AGE.
The unchecked formation of AGE in vivo, such as in diabetics related diseases, can lead to severe physiological impairment. For example, in diabetic neuropathy and retinopathy, the functional integrity of the capillary wall barrier and inner blood retinal barrier, respectively, are defective, as evidenced by the abnormal attachment of the endothelium to the basement membrane. This defect is a direct consequence of the cross-linking of structural proteins by glycation. The etiology of diabetic neurovascular disorders, as well as immunological disorders, is the formation of AGE. Currently, it is believed that inhibiting AGE formation, or the breaking of existing AGE, would be beneficial in a variety of diseases, including nephropathy, neuropathy, arteriosclerosis, and dermatological disorders.
Studies have demonstrated positive effects of agents that break AGE, such as in studies on cardiovascular complications related to aging, a condition which is accelerated in experimental diabetic conditions (Wolffenbuttel et al., 1998).
In another pharmacological approach to controlling levels of AGE in tissues, especially in those tissues in which AGE has already accumulated to levels which are responsible for sub-clinical or clinical pathology, administration of agents that reverse or break AGE has proven successful. As described in U.S. Pat. Nos. 5,656,261 and 5,853,703 agents and methods are disclosed which reverse (or cleave or break) AGE formation in vitro and in vivo.
Several successful therapeutic approaches have also been achieved based upon blocking the accumulation of AGE in vivo. One approach, exemplified in U.S. Pat. No. 4,758,583 concerns the inhibition of the formation of AGE from its precursors, by the administration of agents such as aminoguanidine and related compounds.
As has been shown in the above-cited references, compounds which block AGE formation, or break AGE, are reasonably correlated to the treatment of AGE-related disorders, such as diabetic nephropathy, neuropathy, retinopathy, and arteriosclerosis, dermatological disorders, non-enzymatic browning of the oral cavity, endothelial or other organ dysfunction and growth impairment.
The correlation between the onset of AGE with various diseases has also been described in various literature as discussed below.
The correlation between the formation of Advanced Glycation End products (AGE) and nephropathy is well established by several research publications. Beisswenger (1995) has shown that AGE concentration in human diabetic subjects correlates with early manifestation of renal diseases. Makita et al (1991) has shown that increase in AGE peptides parallels with the severity of renal dysfunction. The above citations clearly show that AGE is the principal cause of diabetic nephropathy. Yamauchi (1997) showed that prevention of AGE formation by aminoguanidine inhibits development of diabetic nephropathy. Aminoguanidine administration is also shown to ameliorate thickening of glomerular basement membrane of diabetic rats (Ellis 1991). Aminoguanidine is also shown to attenuate the rise in albuminuria in experimental diabetic rats (Soulis-Liparota, 1991).
AGE is also shown to induce expression of vascular endothelial growth factor in retinal muller cells (Hirata, 1997, Murata, 1997) and therefore may promote intraocular neovascularization in diabetic retinopathy. Aminoguanidine treatment is shown to retard progression of diabetic retinopathy in rat model (Hammes, 1991, Hammes, 1994, Roufail, 1998).
Aminoguanidine treatment is also shown to improve nerve conduction velocity in diabetic rats (Kihara, 1991 Miyauchi, 1996 and Yagihashi, 1992).
Bucala (1996) has extensively reviewed various aspects of development of Atheroscelrosis and stated that accumulation of AGE can trigger a series of cellular events, such as cellular oxidative stress, expression of adhesion molecules, endothelial transmigration of monocytes, etc. and these events can lead to atherosclerosis. Kirstein (1990) have demonstrated that (i) in vitro and in vivo-formed AGE proteins are chemotactic for human blood monocytes, (ii) sub-endothelial AGE can induce monocyte migration across intact endothelium and (iii) interaction of monocyte with AGE containing matrix results into induction platelet derived growth factor.
Thus, it can be concluded that AGE, upon interaction with endothelial cells through its receptor RAGE, activate nuclear factor Kappa B and induce various genes expressing adhesion molecules. AGE-endothelium interactions also increase oxidative stress, initiate monocyte migration, block endothelial nitric oxide and stimulate angiogenesis. All these conditions result in conditions such as atherosclerosis.
Other dysfunctions demanding lower tissue AGE burden include, Hypertension, Restenosis, abnormal tissue hindrance in peritoneal dialysis, Erectile Dysfunction and Alzheimer disease. Similarly, on the other hand, non-enzymatic cross-linking of structural proteins, such as collagen, leads to increased stiffness of arteries and reduce arterial compliance and distensibility. In fact, treatment of AGE-breaker ALT-711 is shown to reverse diabetes induced increase of arterial stiffness and improve arterial compliance (Wolffenbuttel 1998). Aronson et al (1996) have reviewed role of AGE in promoting inflammatory cell recruitment and smooth muscle proliferation and suggested it to be a likely reason for greater restenosis, abnormal tissue hindrance in peritoneal dialysis rate in diabetic patients.
Seftel (1997) has shown significant elevation of pentosidine in the penile tissue of diabetic patients as compared to non-diabetic. They have speculated a mechanism for AGE mediated erectile dysfunction via upregulation of inducible nitric oxide and downregulation of endothelial nitric oxide in penile tissues.
Vitek et al (1994) have reported that beta amyloid peptides (βAP) aggregate slowly under normal physiological conditions whereas AGE modified (βAP) showed a much more rapid aggregation. Plaque numbers increase in association with neuronal degeneration and cognitive decline in AD. Aggregated but not monomeric βAP is actively neurotoxic. Hence interference with the process by which AGE formation enhances βAP aggregation or inhibition of AGE formation or AGE breaker therapy will provide new therapeutic opportunities to reduce the pathophysiological changes associated with Alzheimer's disease.
Hence AGE inhibitors/breakers would be beneficial in reducing the aggregation of βAP, leading to the prevention/treatment of Alzheimer's disease.
Li et al (1996) have provided evidence for an interrelationship between two key manifestations of physiological aging in the rat cardiovascular and renal decline and the spontaneous age associated biochemical process termed advanced glycation thought to contribute to progressive tissue damage and organ failure. In their study aminoguanidine (an AGE inhibitor) was found to significantly prevent tissue damage as a result of inhibiting AGE formation. Lower tissue AGE burden in rats as a result of aminoguanidine administration was found to preserve an altogether more satisfactory level of cardiovascular and renal function as evidenced by the generally healthier appearance of old rats treated by aminoguanidine as compared to the untreated age and weight matched controls. Hence AGE inhibitors could be used for the prevention of aging related disorders.
The nonenzymatic browning reaction, which occurs in the oral cavity, results in the discoloration of teeth. Anti-plaque agents such as chlorhexidine have been reported to accelerate the non-enzymatic browning reaction and further the staining of teeth. (Nordbo, J. Dent. Res., 58, p. 1429 (1979)). Nordbo has proposed that chlorhexidine results in tooth staining in two ways: first, by increasing the formation of pelicle which contains more amino groups, and secondly, by catalysis of the Maillard reaction leading to colored products.
The ability of inhibitors of non-enzymatic browning reaction to prevent the discoloration of protein on a surface, such as that which occurs on the tooth surface has been demonstrated with in vitro experiments in U.S. Pat. No. 5,137,916; U.S. Pat. No. 5,272,176.
Compounds that have the ability to inhibit or reverse AGE have been claimed to be useful for the inhibiting or reversing the discoloration of teeth resulting from non-enzymatic browning in the oral cavity. (U.S. Pat. Nos. 5,272,176; 5,853,703)
All these evidences point out to a common underlying mechanism for the pathophysiological conditions associated with diabetes and that is the formation of Advanced Glycation Endproducts. As the total tissue burden of AGE increases, the severity of the pathological symptoms too increase. On the other hand, if the quantum of AGE is controlled by the compounds like Aminoguanidine, the progression of disease is also retarded. In the present invention, the inhibition of Advanced Glycation Endproducts is described.
Renal disease is a leading cause of death and diability in diabetes. Chronic dialysis and renal transplantation are quite routine in patients with renal failure due to diabetes. Peritoneal Dialysis (PD) works on the same principle as hemodialysis, but the blood is cleaned while inside the body rather than through a machine. The major difference in peritoneal dialysate formulations as compared to hemodialysis in the amount of higher glucose concentrations used as an osmotic agent (1.5, 2.5 or 4.25 g/dL). High glucose formation in humans is associated with the progressive formation of Advanced Glycosylation End-products (AGE's) that damage organ function. AGE's contribute to the development of abnormal fibrous tissue and reduces the ability of the peritoneum to filter fluids, leading to a failure of the PD procedure.
The compounds which can alter the AGE contents of the tissue could be used to prevent this process and other medical complications arising from the formation of AGE's. Use of an AGE breaker or inhibitor in the dialysis fluid would inhibit formation of abnormal fibrous tissue and thereby facilitate peritoneal dialysis proceduce. Accordingly the compound of the invention can be used for preparation of dialysis fluid for peritoneal dialysis of a diabetic patient.
Reducing the tissue burden of AGE is expected to reverse these conditions, whereas preventing accumulation up to critical mass could prevent the condition from occurring. These conditions are listed bellow:                a. vascular and neuro-vascular complications,        b. nephrological disorder,        c. neurological disorder,        d. atherosclerosis,        e. retinal disorder,        f. dermatological disorder,        g. non-enzymatic browning of oral cavity,        h. endothelial or other organ dysfunction,        i. growth impairment,        j. inflammatory disorder,        k. immunological disorder,        l. oxidative stress,        m. aging and diabetic complication,        n. alzheimer disease,        o. restenosis, abnormal tissue hindrance in peritoneal dialysis,        p. abnormal tissue hindrance in peritoneal dialysis and        q. erectile dysfunction.        
The compounds showing the activity towards breaking/inhibiting AGE can also be useful for their cosmetic utility.
Health, resilience and youthful appearance of the skin depends, among other things, on several key classes of biological molecules. The key skin molecules are collagen and elastin. Collagen is a protein, forming the structural grid that holds other skin structures. It gives the skin its strength and durability. As any other protein, collagen is composed of amino acids. However it is unusually rich in a few specific amino acids; proline, hydroxy proline, lysine and glycine. Elastin is also a protein, more stretchable than collagen and helps to maintain skin resilience and elasticity. It contains two special amino acids: desmosine and isodesmosine. When both elastin and collagen are at scarce and damaged, the skin looses its shape after being stretched or folded leading to wrinkles and facial sag that happens during the process of aging.
Most modern theories of aging have centered around the notion that age-related deterioration is primarily due to structural and functional modifications of cellular constituents. The currently popular hypothesis are the Free Radical, Glycation or Maillard theories of aging. The first hypothesis proposes that age-related effects are due to free radical reactions that damage cellular constituents. “Free radical” refers to an unstable molecule that has an unpaired or odd electron in an outer orbit, which indiscriminately react with other molecules causing lipid, DNA and protein damage. The latter hypothesis propose that the primary cause of aging is cellular damage resulting from the modification of macromolecules induced by non-enzymatic glycation and Maillard reactions to form advanced glycosylation end-products (AGEs). Non-enzymatic glycation is the chemical attachment of sugars to protein that eventually causes protein cross linking, which is irreversible. Although these hypothesis were formulated independently, it suggests that free radicals, glycation, and Maillard reactions may in fact represent partially interactive elements of a single, more complex biochemical pathway, and that age-related deterioration is produced by the sum of the damages induced by all three hypotheses, and by their interactions.
Skin, a highly differentiated and complexly structured organ, is particularly vulnerable to free radical damage on exposure to UV radiation resulting in an increased accumulation of AGEs on the skin as well as an increased production of singlet oxygen and super oxide radicals which damage the important skin molecules such as collagen and elastin. Under such situations an anti-oxidative condition through free radical scavenging would certainly enable the skin to maintain its normal resilience and integrity against damage.
Hence, the present invention is directed towards a cosmetic application with an active molecule capable of reversing the AGE cross links and creating an anti-oxidative environment in tissues through its AGE breaking and free radical quenching actions, thereby significantly slowing down the aging manifestations.
The skin is the largest organ in the body, comprising about 15% of the body weight. In terms of chemical composition, the skin is about 70% water, 25% protein and 2% lipids. The remainder includes trace minerals, nucleic acids, glycosoaminoglycans, proteoglycans and numerous other chemicals.
The skin consists of 3 main layers: Epidermis, dermis, subcutaneous tissue. The epidermis is the first barrier between us and the outside world. This layer consists of 3 types of cells; keretinocytes, melanocytes and langerhans cells. The dermis is the middle layer of the skin, the thickest of the skin layers and comprises a tight, sturdy mesh of collagen (type-I and III) and elastin fibers which are the critically important skin proteins. The dermis also consists of fibroblasts, capillaries, lymph nodes, sebaceous glands, sweat glands and hair follicles. The subcutaneous tissue is the innermost layer of the skin comprising mainly of adipocytes, acts as a shock absorber and heat insulator, protecting underlying tissues from cold and mechanical trauma.
Aging is a biological phenomenon which is symbolized by wrinkles and sagging skin. As a person ages, skin cells divide more slowly, and the inner skin, or dermis, starts to thin. Fat cells beneath the dermis begin to atrophy, and the underlying network of elastin and collagen fibers, which provides scaffolding for the surface layers, loosens and unravels. Skin loses its elasticity; when pressed, it no longer springs back to its initial position but instead sags and forms furrows. The skin's ability to retain moisture diminishes; the sweat- and oil-secreting glands atrophy, depriving the skin of their protective water-lipid emulsions. As a consequence, the skin becomes dry and scaly. In addition, the ability of the skin to repair itself diminishes with age, so wounds are slower to heal. Frown lines (those between the eyebrows) and crow's feet (lines that radiate from the corners of the eyes) appear to develop because of pen-permanent small muscle contractions. Habitual facial expressions also form characteristic lines, and gravity exacerbates the situation, contributing to the formation of jowls and drooping eyelids. Since the skin represents the most visible organ of the aging, there is increasing interest in the physiology and reversal of wrinkles, elastoses and senile xerosis. Cutaneous aging is a complex phenomenon consisting of genetically determined intrinsic and extrinsic aging factors(Boni R, Burg G: Schweiz Med Wochenschr (2000) September 9; 130 (36): 1272–8).
Mainly, there are two biologically independent aging processes that occur simultaneously, which account for the major changes seen in skin over time.
1. Extrinsic aging or Photoaging/External Factors and
2. Innate or Intrinsic aging/Internal Factors
Extrinsic aging or Photoaging, which results when skin is exposed to the elements like Ultraviolet (UV) radiation, Chemical Pollutants, Allergens, Mechanical damage, etc. Extrinsic aging is primarily caused by ultraviolet radiation of the sun.
Intrinsic aging affects skin by slow, irreversible degeneration of tissue. The factors causing intrinsic aging are genetic, nervous (stresses), immune, hormone disorders and others. Intrinsic aging can be observed over the entire surface of the body, including skin protected from ultraviolet radiation of sun. The phenomenon of glycation as discussed above plays a serious part in intrinsic aging. Proteins from dermis, elastin and collagen react with sugars in the body, especially glucose to result in the binding together of collagen fibers and the synthesis of free radicals. This modifies the structure of the skin causing it to loose its suppleness and become more rigid. Thus, the most noticeable changes on facial skin result from a combination of intrinsic and extrinsic aging processes.
Basically two factors—free radicals and ACE formation are the prominent accelerators of skin wrinkles. The Maillard theory of Skin aging dates back to 1912 when Maillard found that reducing sugars such as glucose and ribose react with proteins to form brown pigments. The Maillard reaction is a series of complex reactions that cause the cross-linking of protein via the interaction of reducing sugars with amino groups of proteins to form stable Amadori products, which subsequently cross-link to form Advanced Glycation End products (AGE). Another property of critical biological significance is the observation that the Amadori products continue to cross-link and polymerize even in the absence of free glucose. Protein crosslink is important since it is responsible for deep wrinkling in the dermis. The formation of AGE crosslinks is also a natural part of the aging and all the processes where protein aging is a serious detriment. During the aging process reducing sugar chemically attaches to the skin's support proteins like elastin and collagen, causing them to become gradually rigid and slowing their renewal. This non-specific and non-enzymatic attachment of the sugar to collagen and elastin lead to the formation of AGE which continues to cross-link and polymerize even in the absence of free glucose. The studies on the role of AGEs in aging collagen using scanning force microscope reveal that in the presence of an increased concentration of AGEs, significant structural alterations have been observed in the collagen fibrils of old rats(Odetti P, Aragno I, et al. Gerontology (1998); 44 (4); 187–91). As a result of this aging process, collagen loses its elasticity and the skin develops wrinkles.
The covalent binding of glucose to the amino group of protein alone is not sufficient to account for structural changes observed in collagen. Oxygen radicals formed during glucose oxidation, and glycated protein oxidation may be involved directly in the formation of AGEs and collagen cross-linking. In vitro studies demonstrate that the presence of oxygen is indispensable for the advanced glycation and cross-linking of collagen. Antioxidative condition and free radical scavengers have been proven to inhibit or slow down the formation of AGEs and the cross-linking of collagen. It is also known that free radical scavengers are essential in protecting the epidermis from damage by free radicals generated both by environmental and endogenous factors (Pugliese P T, Dermatol. Nurs (1998) December: 10 (6): 401–16; quiz 417–18).
Skin, which has a highly differentiated and certainly complex organizational structure, is particularly vulnerable to free radical damage because of its contact with oxygen and other environmental stimuli(Calabrese V, Scapagnini G et. al., Drugs Exp. Clin Res. (1999); 25(6): 281–7). Studies have proved that UV radiation increases the formation of AGEs on collagen, elastin and other skin proteins. It forms a vicious cycle by increasing the accumulation of AGEs on the skin as well as increased production of singlet oxygen and super oxide radicals, which damage the skin protein.
With recent years, substantial progress has been made in unraveling, the underlying mechanisms of photoaging. Induction of matrix metalloproteinases as a consequence of activator protein (AP)-1 and Nuclear factor (NF)—kB activation as well as mutations of mitochondrial DNA have been identified recently(Berneburg M, et. al. Photodermatol Photoimmunol. Photomed (2000) December: 16 (6): 238–44). In the early stage of glycation the condensation of reducing sugars such as glucose with amino groups of proteins generates UVA photo generated singlet oxygen free radicals. It is reported that AGE is an important factor for promoting photoaging in the skin via generation of active oxygen species involving O2−, H2O2 and —OH (Masaki H. et. al., Biochem Biophys. Res. Commun (1997) June 18: 235). On the basis of invitro fibroblast studies a possible mechanism is proposed in which AGEs under UVA irradiation generate active oxygen species involving O2−, H2O2 and OH while the OH species place a harmful role in promoting cell damage (Hitoshi Masaki et. al. Biochemica et Biophysica Acta 1428 (1999) 45–56) . These radicals disrupt the natural balance of the skin by stimulating the skin cells to synthesize metalloproteinases. The metalloproteinase enzymes degrade collagen without synthesizing anti-metalloprotenases that keeps a check on the skin protein degradation, which is a normal biological response. The unbalanced production of metalloproteinase over anti-metalloprotenases induced by singlet oxygen free radicals leads to break down of collagen and elastin of the skin. This is followed by imperfect wound repair of damaged collagenous matrix and accumulation of elastotic material, as a consequence the skin sags and wrinkles.
Due to the exposure of AGEs to UV A radiations, the generation of super oxide anion gets enhanced. This is accomplished through cellular electron transfer chain in which UV A-AGEs energy enhances the passing of electrons onto ground state oxygen. This leads to enhanced formation of super oxide, anion during Adenosine Triphosphate (ATP) synthesis. An enzyme super oxide dismutase converts the super oxide anion into hydrogen peroxide and oxygen. Finally, the catalytic action of iron and copper transforms hydrogen peroxide into toxic hydroxyl radical causes the degradation of skin collagen and elastin which is followed by imperfect wound healing and solar scar develop that photoage the skin.
The shelves in the cosmetics market are full of products treating extrinsic aging, but there is still a vacuum for a product, which targets intrinsic aging by inhibiting AGE in skin support proteins.
The ability to inhibit the formation of Advanced Glycation End products (in skin support proteins, like collagen) along with AGE breaker activity and Free Radical Scavenging activity, carries with it significant implications in treatment of Skin aging and wrinkles etc.
Thus, using the molecules, which can alter the presence of AGE, it is possible to prevent the signs of skin aging and wrinkle formation etc., and using them for cosmetic applications.
Experience shows that skin aging and wrinkle formation occur in-spite of good skin care. Hence, there is a need for development of an agent to prevent or treat aging of skin caused by formation of AGE. The compounds of the present invention are non-peptide, capable of modifying the AGE cross-link, formation in Collagen and Elastin. The compounds of the instant invention can be formulated along with other agents into a cosmetic preparation.
To prevent or delay skin wrinkles, it is important to inhibit formation of AGE, to reverse the already formed AGE as well as lower the oxidative stress by means of an antioxidant or free radical scavanger. Essentially a molecule that inhibits AGE; breaks AGE and slows down the formation of AGE and prevents collagen degradation, would be an ideal candidate for cosmeceuticals. The molecules of the instant invention exhibit the properties of being an AGE inhibitor and a potent AGE breaker well as free radical scavenger which make them most suitable for cosmetic applications.
Free radicals are atoms or molecules that have one or more unpaired electrons in their atomic structures and are highly reactive. Free radicals—reactive oxygen species (ROS)—are produced continuously in mammalian systems as a consequence of normal metabolic processes. Exogenous sources of ROS include exercise, pollution (especially cigarette smoke and car exhaust), alcohol, sunlight, and drugs (like anesthetics). Although free radicals have an important role in normal physiologic mechanisms, the excessive production of ROS results in oxidative stress—the terms usually applied to the out come of oxidative damage to biologically important molecules, such as protein, lipids, and nucleic acids. Proteins have long been known to be susceptible to oxidation by ROS. Aromatic amino acids like cystine, and disulfide bonds are particularly vulnerable. All biological materials contain a variety of polyunsaturated fatty acids, which are predominantly located in membrane lipids. They are highly susceptible to damage by ROS.
The group of compounds known as antioxidants (also referred to as “free radical scavengers”) is the major defense against oxidative stress. These compounds function to protect membrane and cytosolic components against damage from ROS. Primary antioxidants, which prevent the formation of new radical species, include enzyme systems such as superoxide dismutase (SOD) and glutathione peroxidase (GSH Px). Secondary antioxidants trap radical species, thus preventing chain reactions, and include nutrients such as vitamin E, vitamin C, taurine and β-carotene. The final line of antioxidant defense is provided by the repair systems such as the enzyme methionine sulfoxide reductase that regenerates methionine residues within oxidized proteins and restores function.
Endogenous oxidative damage to cellular components, primarily proteins, lipids, and DNA is thought to contribute to the pathogenesis of numerous chronic diseases. The association between compromised antioxidant status, indices of oxidative damage, and clinical conditions like diabetes mellitus, asthma, chronic renal failure, hepatitis, colitis, atopic dermatitis, arthritis and various degenerative disorders is now well documented. There is considerable circumstantial evidence linking diminished antioxidant status including enzymes and nonezymatic scavengers, to increased oxidative damage and disease severity.
There is need of the molecules with ability to break/inhibit the protein cross linking, in addition of having anti-oxidant activity so that apart from their use in several disease conditions where oxidative stress plays vital role in the pathogenesis, they can be effectively used for cosmetic applications as mentioned below:    a) reversal and prevention of wrinkles,    b) reversal and prevention of fine lines,    c) promotion of epidermal growth,    d) photo protection of skin,    e) reversal and prevention of skin discoloration,    f) reversal and prevention of age spots,    g) conditioning and prevention of dry spot,    h) reversal and prevention of stretch marks,    i) reversal and prevention of blemishes,    j) skin care and conditioning,    k) reversal and prevention of senile xerosis,    l) conditioning and prevention of sun burns,    m) preventing and reversing the loss of collagen,    n) improving skin texture,    o) improving skin tone,    p) enhancing of skin thickness,    q) decreasing pore size,    r) restoring skin luster,    s) minimising signs of fatigue,    t) reducing acne,    u) treatment of Telangiectasia and    v) improving aesthetic appearance of hair and nails.Pharmaceutical Application of the Free-radical Scavenging (Anti-oxidant) Property of the Molecules.
Apart from the use of the compounds for cosmetic applications based on their AGE-breaking/AGE inhibiting and free-redical scavenging activities, the latter activity of these compounds can be used in strategies directed at control of oxidative stress for effective management of conditions discussed below:
Neuro-degenerative disorders such as Alzheimer's disease (A.D.), Parkinson's disease (P. D.), Huntington's disease (H.D.), Motor neuron disease (M.N.D), Prion disease
As people age, their antioxidant levels diminish and these low levels are directly linked to the many diseases associated with aging such as Alzheimer's and Parkinson's disease. One of the leading hypotheses is that oxidative stress induced by Relative Oxygen Species (ROS) damages essential components of the neurons, resulting ultimately in the neuronal death. Oxidative stress is involved in various divergent events leading to neuronal damage, including an increase in membrane rigidity, DNA strand break, and impairment in glucose uptake. Several potential sources of oxidative stress in different neurodegenerative disorders have been well identified [Munch G, et al. 1998].
In A.D. mitochondrial dysfunction, amyloid beta mediated processes; transition metal accumulation and genetic factors are responsible for the redox imbalance [Smith M A, et al 2000].
Point mutations in Superoxide Dismutase enzymes are known in the familial form of MND.
Disturbances of neuronal energy metabolism have been implicated as a pathogenetic mechanism for H.D. [Browne S E, et al. 1999].